Rustproofing material and method of treating the same



Patented July 12, 1932 PATENT OFFICE VAN M. DARSEY, OI MORENCI,MICHIGAN, ASSIGNOR T PARKER BUST-PROOF OOH- IPAN'Y, 0F DETROIT,MICHIGAN, A. CORPORATION OF MICHIGAN BUSTZPROOFING MATERIAL AND METHODOF TREATING THE SAME No Drawing.

This invention relates to a rust-proofing material and more particularlyto such a material which may be kept in granular or powdered form underusual weather conditions without deterioration. More specifically,

the invention relates to a rust-proofing material comprising granular orpowdered high acid phosphates with a material added thereto fordeterring the drying out of the phosphates.

This invention is applicable to rust-proofing material such as thatdisclosed in the patent to Green et al on. rust-proofing, No. 1,651,694,dated December 6, 1927, and which includes phosphates of the metals ofthe electromotive series from manganese to iron, inclusive, andcorresponding substantially to the formula M (H PO 2.

Rust-proofing material such as that dis- :0 closed and claimed in theabove cited patent contains a certain amount of water when first formed.Some of this is water of crystallization and some of it is doubtlesspresent in other forms. When the freshly formed ma- :5 terial is ex osedto the air at ordinary temperatures t ere is generally a slight initialloss of weight by drying and a subsequent absorption of moisture fromthe atmosphere to equal or exceed the original weight of the 80material. The freshly ormed material is more readily soluble in arust-proofing bath than is the material after it has dried to thisslight extent and then reabsorbed moisture. The appearance of thecrystals undergoes a change during this initial loss and subsequentreabsorption of moisture, which can be detected under the microscope,the older crystals being rougher in appearance than those first formed.These differences in the characteristics of the material after initialloss of weight and subsequent reabsorption indicates that there is somediflerence in the nature of the moisture present, but just what thisiscannot be stated at the present time.

When material such as that described Application filed November 15,1928. Serial No. 819,733.

above has gone through this initial slight drying stage and subsequentabsorption of water, and s exposed to temperatures as high as aregenerally attained in the United States during the summer time, itfrequently cakes to a greater or less extent. This cakmg does not seemto seriously afiect its chemical composition, so that if it is regroundit may be used readily for rust-proofing purposes, and with nearly itsinitial efiiciency. But unless it is Sub ected to a somewhat troublesomeprocess for breaking up the lumps and regrinding it is not assatisfactory for forming a rust-proofing bath, as the lumps dissolvemuch more slowl and are likely to become covered with se iment beforeentirely dissolved, so that their solution is never completed. For thisreason some means is desirable for preventing such caking and lumping ofthe material when exposed to summer temperature.

It has been found that this lumpin of the material can be effectivelyrevented y preventing the initial dryingo the material. As long as thematerial is prevented from undergoing this initial drying step, themoisture seems to remain present in its original relation to thecrystals and the crystals retain their original characteristics. Thematerial which has been so treated as to retain its original moistureretains also its accompanying original characteristics and not onlyhandles morereadily, because it does not undergo lumping, but also issomewhat more readily soluble and, therefore, more eflicient as arust-proofing material.

This initial dryingof the material may be prevented by hermeticallysealing the material immediately after its formation so as tomechanically prevent the escape of moisture from the container. Thedrying out may be prevented also by mixing therewith various materialswhich have the property of retaining moisture. There are many suchmaterials well known, and which, therefore,

do not require enumeration. While there are a great many differentsubstances which would accomplish'the purpose of retaining the initialmoisture of thephosphate crystals and maintaining the material in itsoriginal condition, most of these materials are objectionable asadulterants for various reasons.

It will be obvious that if the material does not dissolve in therust-proofing bath it will necessarily form a sediment which increaseswith the successive replenishments of the bath, thus adding to thesludge in the bottom of the tank. While thisis not an insuperableobjection,-it is an undesirable feature and one wlhlich is'to be avoidedif conveniently poss1 e. a a. r

Of materials which will perform the desired function of retainingmoisture and which. are solubleat least to some extent in therust-proofing bath, there are some which are positively injurious'to theefiiciency of the bath, even in small quantities. Furthermore, anymaterial which is soluble in the bath and which is added repeatedly inthe powder used to replenish the bath, tends to increase in the bathuntil it reaches an objectionable amount, unless there is someway inwhich it is automatically removed.

Of the materials which have been tried for preventing the lumping of thepowder and retaining it in its original condition by preventing itsdrying out, the most satisfactory are zinc carbonate, sugar and boracicacid. Of these three materials, boracic acid is preferred because it notonly is not-detrimental to the efliciency of the bath, at least in thesmall amounts necessary to accomplish the purpose of this invention, butalso during the boiling of the solution it volatilizes sufficiently toprevent detrimental building up in a the bath. Under ordinary conditionsas small an amount of boracic acid as 1% by weight of the phosphatepowder effectively prevents the detrimental drying out of the powder. Aless amount has some beneficial-effects and a greater amount can be usedwithout any noticeable detrimental effect upon the bath.

For that reason the exact percentage of boracic acid added to the powderfor the purpose of preventing drying out and subsequent lumping may bevaried within considerable limits. The practice at present preferred forcommercial purposes is the use of from 1 to 3%, but in its broader scopethe invention is not limited to this percentage. Also, while boracicacid is the best material thus far discovered, there are othermaterials, notably sugar and zinc carbonate, which can be used withconsiderable benefit, and even other materials, less satisfactory fromthe standpoint of subsequent use in the bath, can be effectivelyutilized for the purpose of preventing the drying out and caking of thepowder. For these reasons various materials in various amounts may beadded to the phosseries from manganese to iron, inclusive, in

granular or pulverulent form, which comprises preventing the drying outof such materials from the time of their formation until they are to'beused by dissolvingin a rustproofing bath, and thereby preventing thechange in the relation of the water associated with the material andconsequent lumping or caking of the material which might otherwise.occur.

2. The method which consists in forming crystals of high acid phosphateof manganese,

separating the crystals from their mother liquor, and thereafter, andbefore the crystals dry out, mixing therewith boracic acid.

3. A rust-proofing material comprising high acid phosphates of metalssuitable for forming a rust-proofing bath for iron or steel, andcontaining a material which deters the drying out of the phosphate andthereby prevents lumping and caking.

4. A rust-proofing material comprising crystalline high acid phosphatesof metals of the electromotive series from manganese to iron, inclusive,and a material added to the crystals immediately after their separationand adapted to deter the drying out of said crystals.

5. A rust-proofing material comprising high acid phosphates of metalsof'the electromotive series from manganese to iron, inclusive, ingranular or pulverulent form and containing boracic acid.

6. A rust-proofing material comprising high acid phosphates of metals ofthe electromotive series from manganese to iron, in-

clusive, in granular or pulverulent form and ing, added to said crystalsafter their formation and before drying out occurs, sufiicient boracicacid to deter the drying out of the crystals and a change of therelation of the water to the phosphates resulting in caking or lumping.v

8. A rust-proofing material comprising manganese dihydrogen phosphateingram lar or pulverulent form, and from 1% to 3% of boracic acid.

9. The method which consists in forming crystals of high acid phosphateof manganese, separating the cr stals from their mother liquor, andtherea er and before the crystals dry out mixing therewith boracic acid.

In testimony whereof I have hereunto signed my name to-thisspecification. O

VAN M. DARSEY.

